Light emitting diode package and manufacturing method thereof

ABSTRACT

The present invention relates to a light emitting diode package and a manufacturing method thereof. 
     The light emitting diode package includes a substrate, an LED chip mounted on an upper part of a substrate, a molding material coated at the upper part of the substrate including an external surface of the LED chip, and an encapsulant coated at a lower part of the substrate and can improve luminous efficiency, minimize a package failure, and reduce a manufacture cost by facilitating the manufacturing process.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No.10-2008-0117310 filed with the Korea Intellectual Property Office onNov. 25, 2008, the disclosure of which is incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light emitting diode package and amanufacturing method thereof; and, more particularly, to a lightemitting diode package capable of improving luminous efficiency bydirectly coating a surface of a light emitting diode device (hereinafterreferred to as ‘LED chip’) with a fluorescent material and amanufacturing method thereof.

2. Description of the Related Art

An LED (Light Emitting Diode) is a semiconductor device capable ofimplementing multicolored light by constructing a light emitting sourcethrough a change of compound semiconductor material such as GaAs,AlGaAs, GaN and InGaInP.

Recently, due to rapid development of a semiconductor technology, theLED can be produced with high brightness and high quality in comparisonwith a general-purpose product with low brightness. Further, as blue andwhite LEDs with an excellent characteristic have been implemented, anapplication range of the LED has been broadened to a display, anext-generation illumination source, and so on.

Such an LED is mainly manufactured in a package type and an LED packageincludes a package mold having a molding material filling space by beingcoupled to a pair of lead frames, an LED chip mounted on the lead framespositioned inside the package mold, a wire for electrically connectingthe LED chip and the lead frames, and a molding material for protectingthe LED chip and a portion of the wire by being filled inside thepackage mold.

At this time, in the conventional LED package, the molding material canbe made of light-transmitting resin mixed with a predetermined amount offluorescent material in order to implement a white LED package.

Such a conventional LED package electrically connects the lead framesand the LED chip through the wire, wherein both ends of the wire areconnected to power by being bonded to the lead frame and the LED chiprespectively and one end of the wire of which the other end is bonded toa top surface of the LED chip is connected to the lead frame.

In other words, there is no option but to fill the molding material onlyby a dispensing method because the wire is positioned at an upper partof the LED chip mounted inside the package mold, thereby deterioratingworkability.

Further, if a mixture of silicon and fluorescent material is injectedinside the package mold for white light-emitting of the LED chip at thesame time when the LED chip mounted inside the package mold is fixed andsealed, the fluorescent material is exposed outside the package moldthrough the wire, which causes a package failure.

And, a problem has been pointed out that luminous efficiency is reducedbecause the fluorescent material for white light-emitting of the packageis coated only on a surface of the LED chip.

SUMMARY OF THE INVENTION

The present invention has been proposed in order to overcome theabove-described problems and it is, therefore, an object of the presentinvention to provide a light emitting diode package which is coated witha fluorescent material to be in contact with a surface of an LED chipmounted at an upper part of a lead frame and encapsulated at a lowerpart of the lead frame by using an encapsulant including a reflectionmaterial.

Further, it is another object of the present invention to provide alight emitting diode package not to contact a fluorescent material forwhite light-emitting of an LED chip with a wire by implementing electricconnection between the LED chip and a lead frame through the wire on abottom surface of the lead frame mounting the LED chip.

In accordance with one aspect of the present invention to achieve theobject, there is provided a light emitting diode package including: asubstrate; an LED chip mounted on an upper part of a substrate; amolding material coated at the upper part of the substrate including anexternal surface of the LED chip; and an encapsulant coated at a lowerpart of the substrate.

At this time, the substrate and the LED chip are electrically connectedby being bonded with wires and the wires electrically connect a bottomsurface of the substrate and a bottom surface of the LED chip.

Therefore, since a substrate mounted surface and a wire-bonded surfaceof the LED chip are formed on the same surface, a fluorescent materialcoated at an upper part of the LED chip is not in contact with thewires.

Further, the encapsulant coated at the lower part of the substrate canbe made of transparent resin and light emitted from the LED chip isreflected at the encapsulant by including a reflection material in thetransparent resin and can be emitted through the fluorescent material ofthe upper part.

At this time, it is preferable that the substrate is made oflight-transmitting material in order to reflect light emitted from theLED chip through the encapsulant including the reflection material.

Further, the molding material covers a top surface of the LED chip andall sides of lateral parts of the LED chip by being coated at the upperpart of the substrate and is made of resin including the fluorescentmaterial, wherein it is preferable that the resin is formed by mixingthe fluorescent material and the silicon at a predetermined ratio.

And, a reflection layer can be formed on a top surface of the substrateor the external surface of the LED chip and can be formed on both thesubstrate and the LED chip.

Meanwhile, in accordance with another aspect of the present invention toachieve the object, there is provided a manufacturing method of a lightemitting diode package including the steps of: forming through holes ona flat-panel type substrate at equal intervals; mounting LED chips atupper parts of the through holes to cover the through holes of thesubstrate; bonding the LED chips and the substrate with wires; coating atop surface of the substrate with a molding material to cover all sidesand top surfaces of the LED chips; coating a bottom surface of thesubstrate with an encapsulant to encompass the bonded wires; and aftercuring the molding material and the encapsulant, cutting the lightemitting diode package into unit light emitting diode packages alongdicing lines.

It is preferable that the substrate includes a plurality of throughholes at equal intervals and the through holes are formed in sizes to becovered by the LED chips.

The molding material coated on an upper part of the substrate isentirely coated in order to bury the LED chips mounted at the upper partof each of the through holes of the substrate and is made of resin mixedwith a yellow, red or green fluorescent material.

Further, the encapsulant is coated on the bottom surface of thesubstrate to bury the wires electrically connected by being bonded tothe LED chip and is made of transparent resin or resin including areflection material.

The molding material and the encapsulant can be coated at predeterminedthicknesses by any one of coating methods such as squeeze, screenprinting, silk screen, and stencil.

At this time, in the light emitting diode package, the molding materialand the encapsulant can be coated by a dispensing method and when themolding material and the encapsulant are coated by the dispensingmethod, the light emitting diode package can be manufactured bydispensing the molding material and the encapsulant to the upper andlower parts of the substrate after manufacturing an individual package.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present generalinventive concept will become apparent and more readily appreciated fromthe following description of the embodiments, taken in conjunction withthe accompanying drawings of which:

FIG. 1 is a cross-sectional view illustrating a light emitting diodepackage in accordance with one embodiment of the present invention;

FIGS. 2 to 7 are views showing a manufacturing method of a lightemitting diode package in accordance with the present invention;

FIGS. 2A and 2B are a perspective view and a cross-sectional viewshowing a substrate employed during the manufacturing method of thelight emitting diode package in accordance with the present embodiment;

FIGS. 3A and 3B are a perspective view and a cross-sectional viewshowing a state in which LED chips are mounted to the substrate employedduring the manufacturing method of the light emitting diode package inaccordance with the present embodiment;

FIG. 4 is a cross-sectional view illustrating a case in which thesubstrate and the LED chips employed in the light emitting diode packagein accordance with the present embodiment are bonded with wires;

FIG. 5 is a cross-sectional view illustrating a case in which a moldingmaterial is coated during the manufacturing method of the light emittingdiode package in accordance with the present embodiment;

FIG. 6 is a cross-sectional view illustrating a case in which anencapsulant is coated during the manufacturing method of the lightemitting diode package in accordance with the present embodiment; and

FIG. 7 is a cross-sectional view illustrating a cutting process duringthe manufacturing method of the light emitting diode package inaccordance with the present embodiment.

DETAILED DESCRIPTION OF THE PREFERABLE EMBODIMENTS

A matter regarding to an operation effect including a technicalconfiguration for the objects of a light emitting diode package and amanufacturing method thereof in accordance with the present inventionwill be clearly appreciated through the following detailed descriptionwith reference to the accompanying drawings illustrating preferableembodiments of the present invention.

Structure of Light Emitting Diode Package

At first, FIG. 1 is a cross-sectional view illustrating a light emittingdiode package in accordance with one embodiment of the presentinvention.

As shown in the drawing, in accordance with the embodiment of thepresent invention, the light emitting diode package 100 includes asubstrate 110, an LED (Light Emitting Diode) chip 120 mounted on thesubstrate 110, and a molding material 130 and an encapsulant 140 coatedat upper and lower parts of the substrate 110 at predeterminedthicknesses.

The substrate 110 is formed in a flat-plane shape with a through hole111 (see FIG. 2) at a central part and the LED chip 120 is mounted on acircumferential part inside the substrate 110 including the through hole111.

A bottom surface of the LED chip 120 is supported to a top surface ofthe substrate 110 and at this time, the LED chip 120 and the substrate110 are electrically connected through wires 150.

The wires 150 electrically connect the LED chip 120 and the substrate110 by bonding one ends of the wires 150 to the bottom surface of theLED chip 120 and bonding the other ends thereof to a bottom surface ofthe substrate 110 and the wires 150 of which the one ends are coupled tothe bottom surface 120 of the LED chip 120 mounted on the substrate 110,are drawn out and so the other ends thereof are coupled to the bottomsurface of the substrate 110.

In other words, as the bottom surface of the LED chip 120 is received onthe top surface of the substrate 110 and the one ends of the wires 150are bonded inside a substrate-received surface of the LED chip 120,support and wire-bonding of the LED chip 120 are implemented on thebottom surface of the LED chip 120 as the same surface as thesubstrate-received surface.

Further, the molding material 130 is coated on the top surface of thesubstrate 110 mounting the LED chip 120. The molding material 130 iscoated at an upper part of the substrate 110 at a predetermined height,wherein it is preferable that it is coated at the height higher than theLED chip 120 in order to bury the LED chip 120 mounted on the substrate110.

The molding material 130 is coated on the substrate 110 by being mixedwith a fluorescent material for emitting light from the LED chip 120 aswhite light and silicon resin for fixing the LED chip 120.

When the molding material 130 is coated on the top surface of thesubstrate 110, it is directly in contact with the top surface of the LEDchip 120 and all sides exposed to lateral parts thereof in order toimprove luminous efficiency when the light emitted from the LED chip 120is emitted through the fluorescent material of the molding material 130.

Further, the molding material 130 can be formed by mixing the siliconresin with a yellow, red or green fluorescent material and the variouscolors of the fluorescent material and a light-emitting color of the LEDchip 120 are combined in order to emit the light emitted through themolding material 130 mixed with the fluorescent material as the whitelight.

For instance, in case that the LED chip 120 mounted on the substrate 110is an LED chip 120 which emits blue light, the white light can beemitted by using resin which is mixed with the red fluorescent materialor the green fluorescent material.

At this time, the fluorescent material can employ any one of a silicatebased fluorescent material, an oxide based fluorescent material, anitride based fluorescent material, and an oxy-nitride based fluorescentmaterial.

Meanwhile, the encapsulant 140 which is mainly made of transparent resinis coated on the bottom surface of the substrate 110 coated with themolding material 130.

The encapsulant 140 is formed to protect the wires coupled forelectrical connection between the substrate 110 and the LED chip 120 andthe bottom surfaces of the LED chip 120 and the substrate 110 and it iscoated on the bottom surface of the substrate 110 at a height at whichthe wires can be buried.

It is preferable that the encapsulant 140 is made of transparent resinor resin including the reflection material.

In case that the encapsulant 140 is made of the resin including thereflection material, the light emitted from the LED chip 120 mounted onthe substrate 110 is reflected at the reflection material inside theencapsulant 140 and emitted outside through the molding material 130including the fluorescent material of the upper part, thereby enhancingluminous efficiency of the LED chip 120.

At this time, it is preferable that the substrate 110 on which themolding material 130 and the encapsulant 140 are separately coated ismade of light-transmitting material with relatively highlight-transmissivity so that the light emitted from the LED chip 120 canbe easily reflected at the encapsulant 140 including the reflectionmaterial.

Meanwhile, a reflection layer can be formed on the bottom surfaces ofthe substrate 110 and the LED chip 120 and the reflection layer can beformed on both the substrate 110 and the LED chip 120.

Manufacturing Method of Light Emitting Diode Package

FIGS. 2 to 7 are views showing a manufacturing method of a lightemitting diode package in accordance with the present invention.

FIGS. 2A and 2B are a perspective view and a cross-sectional viewshowing a substrate employed during the manufacturing method of thelight emitting diode package in accordance with the present embodiment.As shown in the drawings, at first, the flat panel type substrate 110 isprepared and a plurality of through holes 111 are formed on thesubstrate 110 at equal intervals.

FIGS. 3A and 3B are a perspective view and a cross-sectional viewshowing a state in which LED chips are mounted on the substrate employedduring the manufacturing method of the light emitting diode package inaccordance with the present embodiment. As shown in the drawings, aplurality of LED chips 120 are mounted on a top surface of the substrate110 including the through holes 111 in order to cover the through holes111.

The LED chips 120 are individually received on circumferential partsinside the substrate 110, i.e., the top surface of the substrate 110outside the through holes 111 which are formed on the substrate 110 bybeing coupled to the through holes 111 one to one

Then, FIG. 4 is a cross-sectional view illustrating a case in which thesubstrate and the LED chips employed in the light emitting diode packagein accordance with the present embodiment are bonded with wires. In thepresent embodiment, the substrate 110 and the LED chips 120 areelectrically connected to each other by being bonded through the wires150.

As the wires 150 are bonded to bottom surfaces of the substrate 110 andthe LED chip 120 in order to electrically connect both the members,substrate-received surfaces and wire-bonded surfaces of the LED chips120 can be formed on the same surface.

Further, FIG. 5 is a cross-sectional view illustrating a case in which amolding material is coated during the manufacturing method of the lightemitting diode package in accordance with the present embodiment. Asshown in the drawing, the molding material 130 is coated at an upperpart of the substrate 110 at a predetermined thickness after mountingthe LED chips 120 on the top surface of the substrate 110 and bondingthe substrate 110 and the LED chips 120 through the wires 150.

The molding material 130 is made of resin mixed with a fluorescentmaterial and silicon and the mixed fluorescent material in the moldingmaterial 130 can be a blue, red or green fluorescent material.

At this time, it is preferable that the molding material 130 is formedat the thickness at which the LED chips 120 received on the substrate110 can be buried.

Further, since light emitted from the LED chips 120 is reflected at abottom surface of the substrate 110 or the bottom surfaces of the LEDchips 120 and emitted upward through the molding material 130 mixed withthe fluorescent material, luminous efficiency of the LED chips 120 canbe improved.

Then, FIG. 6 is a cross-sectional view illustrating a case in which anencapsulant is coated during the manufacturing method of the lightemitting diode package in accordance with the present embodiment. Asshown in the drawing, after coating the top surface of the substrate 110with the molding material 130 mixed with the fluorescent material, theencapsulant 140 is coated on the bottom surface of the substrate 110 ata predetermined thickness.

It is preferable that the encapsulant 140 is formed on the bottomsurface of the substrate 110 at the thickness at which the wires 150 canbe sufficiently buried in order to protect the bonded wires 150 toelectrically connect the substrate 110 and the LED chips 120.

Further, although the encapsulant 140 is mainly made of transparentresin, it can be made of resin mixed with a reflection material in orderto improve the luminous efficiency of the LED chips 120.

At this time, the reason why the encapsulant 140 is made of the resinmixed with the reflection material is to improve luminous efficiency ofthe light emitting diode package by totally reflecting the light emittedfrom the LED chips 120 to the reflection material of the encapsulant 140positioned at a lower part and emitting the light upward through themolding material 130 wrapping the LED chips 120.

Meanwhile, the molding material 130 and the encapsulant 140 can becoated on upper and lower parts of the substrate 110 by a coating methodsuch as squeeze, screen printing, silk screen, and stencil.

Meanwhile, the molding material 130 and the encapsulant 140 can becoated on upper and lower surfaces of the substrate 110 at apredetermined thickness by a dispensing method. At this time, in casethat the molding material 130 and the encapsulant 140 are formed by thedispensing method, after the substrate 110 with one through hole 111 isindividually formed firstly and the LED chip 120 is individually mountedon the substrate 110, the molding material 130 and the encapsulant 140are formed at the upper and lower parts of the substrate 110 throughdispensing.

Therefore, in case that the molding material 130 and the encapsulant 140are formed by the dispensing method, the following cutting process for aunit package can be omitted in manufacturing the light emitting diodepackage of the present embodiment.

Lastly, FIG. 7 is a cross-sectional view illustrating a cutting processduring the manufacturing method of the light emitting diode package inaccordance with the present embodiment and as shown in the drawing,after curing the molding material 130 and the encapsulant 140 coatedwith respect to the substrate 110, the light emitting diode package iscut along dicing lines in order to manufacture unit light emitting diodepackages.

As described above, the light emitting diode package and themanufacturing method thereof of the present invention can improve theluminous efficiency by directly contacting the molding material mixedwith the fluorescent material with the external surface of the LED chipto form the molding material at the predetermined thickness and byreflecting the light emitted from the LED chip at the encapsulantincluding the reflection material.

Further, the present invention can reduce a package failure caused whenthe fluorescent material spreads along the wires by preventing the wiresfor electrical connection between the substrate and the LED chip frombeing directly in contact with the fluorescent material by bonding thewires to the lower part of the LED chip and reduce a manufacture cost byfacilitating the manufacturing method.

As described above, although the preferable embodiments of the presentinvention have been shown and described, it will be appreciated by thoseskilled in the art that substitutions, modifications and changes may bemade in these embodiments without departing from the principles andspirit of the general inventive concept, the scope of which is definedin the appended claims and their equivalents.

What is claimed is:
 1. A light emitting diode package, comprising: asubstrate formed of a light-transmitting material and having a throughhole formed therein; an LED (Light Emitting Diode) chip mounted on anupper part of the through hole of the substrate, the LED chip emittinglight when an electrical signal is applied thereto; a molding materialcoated on an upper part of the substrate including an external surfaceof the LED chip; and an encapsulant coated on a lower part of thesubstrate, the encapsulant including a resin and a reflective materialdistributed in the resin, wherein: the substrate and the LED chip areelectrically connected by bonding one ends of wires to a bottom surfaceof the LED chip and bonding the other ends of the wires drawn from awire-bonded surface of the LED chip to a bottom surface of thesubstrate, the wires are formed through the through hole, side surfacesof the coated molding material, side surfaces of the substrate and sidesurfaces of the coated encapsulant are substantially coplanar, thesubstantially coplanar surfaces form outer surfaces of the LED package,the molding material is made of resin mixed with a fluorescent material,is molded around the LED chip mounted on the substrate to be directly incontact with a top surface of the LED chip and side surfaces of the LEDchip, and is coated with a predetermined thickness thereon, the moldingmaterial has a wave-length conversion feature, the encapsulant has areflectivity feature, and the substrate has a transparency feature, andthe molding material and the encapsulant, having different opticalfeatures including wave-length conversion and reflectivity, from eachother, are not directly in contact with each other and are separated bythe substrate having the transparency feature.
 2. The light emittingdiode package of claim 1, wherein the through hole is formed at acentral part of the substrate and the LED chip is received at an upperpart of the through hole to cover the through hole.
 3. The lightemitting diode package of claim 2, wherein the through hole is formed ina size to be covered by the LED chip mounted on the substrate and abottom surface of the LED chip is received at a circumferential partinside the substrate including the through hole.
 4. The light emittingdiode package of claim 1, wherein the fluorescent material is any one ofa blue, red or green fluorescent material.
 5. The light emitting diodepackage of claim 1, further comprising: a plurality of wires formedthrough the through hole, wherein each of the plurality of wires has oneend bonded to a bottom surface of the LED chip, and the other end drawnfrom a wire-bonded surface of the LED chip bonded to bottom surface ofthe substrate.
 6. The light emitting diode package of claim 1, whereinthe coated encapsulant encompasses the bonded wires.
 7. The lightemitting diode package of claim 1, wherein the coated encapsulant coversthe entirety of the bottom surface of the substrate.
 8. The lightemitting diode package of claim 7, wherein the coated encapsulantencompasses the bonded wires.
 9. The light emitting diode package ofclaim 1, wherein the substantially coplanar surfaces include the sidesurfaces of the molding material, the side surfaces of the substrate andthe side surfaces of the encapsulant, in this order in a direction ofthickness of the substrate.